Working in the Penumbra of Understanding

By William S. Hammack, John L. Anderson

At their core, science and engineering have different goals and thus different methods. As Theodore von Kármán, an engineer who received the first National Medal of Science in 1962, put it, “Scientists study the world as it is, engineers create the world that never has been.” Engineers solve problems by creating artifacts or systems, often before scientific understanding is available and before the public has identified a need. And the practice of engineering is defined by process, not by one’s field of study.

Understanding and enhancing engineering’s unique process have become vitally important as the nation seeks to reimagine science and technology policy to solve important problems and drive economic competitiveness for the future. The recognition of engineering’s distinctive processes should of course be integral to the planning of big initiatives like infrastructure investment, but it must also be brought to bear on the proposed new directorate at the National Science Foundation. We argue that, to understand what innovation means and how it can be harnessed for national goals, it is crucial to understand engineering’s perspective.

Distinguishing the scientific and the engineering methods

Perhaps the most distinctive feature of the engineer’s perspective is the way knowledge is applied in practice. The method used by engineers to create artifacts and systems—from cellular telephony, computers and smartphones, and GPS to remote controls, airplanes, and biomimetic materials and devices—isn’t the same method scientists use in their work. The scientific method has a prescribed process: state a question, observe, state a hypothesis, test, analyze, and interpret. It doesn’t know what will be discovered, what truth will be revealed. In contrast, the engineering method aims for a specific goal and cannot be reduced to a set of fixed steps that must be followed. In fact, its power lies exactly in that there is no “must.” As mechanical engineer Billy Vaughn Koen has said, “The engineering method is the use of heuristics to cause the best change in a poorly understood situation within the available resources.”

The engineering method aims for a specific goal and cannot be reduced to a set of fixed steps that must be followed. In fact, its power lies exactly in that there is no “must.”

A heuristic, or rule of thumb, is an imprecise method used as a shortcut to find the solution to a problem. The idea is so old and pervasive that practically every language seems to have its own corresponding term: while in English we speak of the thumb, in French it is the nose, in German the fist, in Japanese “measuring with the eye,” and in Russian “by the fingers.” In practice, it’s anything that can plausibly aid the solution of a problem but is not justified from a scientific or philosophical perspective, either because it doesn’t need to be or because it can’t be justified through anything other than results. The specialized skill, the defining trait, and the great creativity of engineering all lie in finding the correct strategy to reach a goal—selecting among and combining the heuristics that will lead to a solution, regardless of whether a deep scientific understanding exists.

One obstacle to leveraging this unique perspective in service of national science and technology policy is the popular notion that science discovers, while engineering applies. This perception—which, among other things, can lead to funding being directed to headline-worthy “breakthroughs” rather than toward real innovation—was aptly caricatured by Walter Vincenti in 1990. “Modern engineers,” he said, “are seen as taking over their knowledge from scientists and, by some occasionally dramatic but probably intellectually uninteresting process, using this to fashion material artifacts.” This traditional “linear model” of the relationship between science and engineering—popularized by Vannevar Bush’s postwar manifesto, Science, the Endless Frontier(1945), the foundational document for federal funding of basic research—suggests that engineering is simply applied science. In this view, someone else observes and explains a phenomenon before an engineer uses it to create something.

But the truth is that engineering often precedes science. The nineteenth century provides a wealth of examples. Scientific observations in this period eventually led to a new scientific understanding of the world, from chemistry and medicine to electromagnetics and quantum physics. But before this new knowledge crystallized, engineers used principles from these subjects to change the world, as illustrated in a few examples. Chemists synthesized long rubbery molecules, but as they puzzled about the nature of those particles, Hilaire Bernigaud spun miles and miles of “Chardonnet silk”—the first synthetic fiber, better known as rayon. Similarly, scientists discovered that a current passed through cables could control a magnetic needle, a baffling phenomenon intractable to the theories of the time, while engineers built vast telegraphic systems under the ocean. And in 1873 Willoughby Smith observed photoconductivity in selenium while working on submarine cables. The phenomenon mystified physicists, but an engineer used the photoconductivity of glassy selenium to create a photocopier in 1938—some 30 years before scientists fully understood it in amorphous materials.

As these examples illustrate, to view engineering as applied science is to conflate the tool with the method. One might think that as science has progressed beyond the nineteenth century, it has steamrolled all uncertainty and replaced engineering’s heuristics with firm calculations from first principles. In fact, nothing of the sort happens, because as scientific knowledge advances, engineering goes beyond that knowledge. The relationship between science and engineering is therefore complementary, synergistic, and essential. Scientific practice and knowledge offer engineers gold-plated, grade A heuristics that work better than those based merely on observation or long periods of trial and error; but this scientific knowledge does not explain how to design or create an artifact or a system. Scientists, in turn, use the products of engineering to investigate and discover.  

Engineering’s goal orientation

Another distinctive feature of the engineering perspective is its focus on achieving particular goals. This orientation is exemplified in the invention and development of the cell phone. In Cutting the Cord, Martin Cooper lays out the vision he and his Motorola colleagues had that went beyond the science and technology of the time: that any person could talk directly to any other person anywhere in the world using a handheld device. Many technical barriers presented themselves, including limited basic scientific understanding of electromagnetic wave propagation in the Earth’s atmosphere, lack of a built environment and of cellular networks with multiple users, and lack of the high-density integrated circuitry needed to miniaturize the phones themselves. But the Motorola team was not deterred by these challenges; they developed both the scientific understanding and the electronic components needed to produce the first prototype handheld device (the DynaTAC), with which Cooper made the first cellular call on April 3, 1973. Had these engineers waited for the relevant science to be known and the miniaturized integrated circuits to be developed, the emergence of cell phones and their descendant smartphones would have been delayed many decades.

As scientific knowledge advances, engineering goes beyond that knowledge. The relationship between science and engineering is therefore complementary, synergistic, and essential.

Another example of the goal orientation of engineering can be found in a cutting-edge and still-evolving science of the last 50 years: molecular biology. Deciphering the code of life embedded in DNA opened a deep and rich mine of knowledge about how organisms work. As understanding deepened, scientists became interested in customizing enzymes, nature’s catalysts, to tackle tasks beyond those assigned by nature. But complexity stymied progress: an enzyme is composed of roughly 500 amino acids, and there are about 20 different amino acids, which means there are 20⁵⁰⁰ possible combinations of amino acids of enzyme length—a mind-bogglingly large number, well beyond the number of atoms in the universe. While efforts to find new and useful combinations among the astronomical possibilities baffled scientists, Frances Arnold, a chemical engineer, created enzymes that reduce the environmental costs of producing fuels, pharmaceuticals, and chemicals.

Arnold determined that she needed enzymes that work under the conditions of an industrial process rather than those of their natural environments. To create these new enzymes, she pioneered the method of “directed evolution,” which does not require a fundamental understanding of how the amino acid sequence encodes an enzyme’s function. Her first engineered enzyme was synthetically evolved from a member of the group that enables humans to digest milk. These enzymes work well in the water-rich liquids of the small intestine, but when Arnold put them in an organic solvent called dimethylformamide (similar to paint stripper), they no longer “digested” milk proteins. To solve this problem, Arnold simulated evolution by creating mutated versions of the enzyme, changing an amino acid or two, and then testing their function. Most of these modified enzymes failed to digest the milk protein, but a few managed to succeed, at least partially. She selected the best new enzyme, created mutated versions of it, and tested again. After ten rounds of mutations and selection in increasingly higher concentrations of the solvent, she engineered an enzyme that worked in a harsh chemical environment almost as well as the original did in water.

Arnold’s idea of directed evolution met resistance from scientists, who protested that her work wasn’t science because it didn’t contribute to the understanding of protein function. She responded that her goal was the engineer’s guiding principle of “getting useful results quickly.” When she accepted the 2018 Nobel Prize for Chemistry for this work, she elegantly stated a key attribute of engineering practice: “A wonderful feature of engineering by evolution is that solutions come first; an understanding of the solutions may or may not come later.” That deep understanding of enzymes has yet to arrive: “even today,” she notes, “we struggle to explain” how her evolved enzymes work. This is a clear reminder that as knowledge about the universe expands, an engineer will always be out front working in the penumbra of understanding, where advances move the borderline between certainty and uncertainty.

“A wonderful feature of engineering by evolution is that solutions come first; an understanding of the solutions may or may not come later.”

To work at the margins of solvable problems and step beyond current scientific knowledge is the raison d’être of engineering. To design something useful without complete scientific understanding signals that an engineer is at work. Engineers often don’t wait until scientists thoroughly understand a phenomenon because the public cannot wait for science. In the absence of complete information, engineers for centuries have created structures, devices, and systems that revolutionized the world—ocean-crossing airplanes, lifesaving medicine, glass and steel towers, lithium-powered cell phones, cellular networks, and spacecraft journeying outside our solar system. All these and more were created by the most powerful problem-solving method available to humans: the engineering method.

Facilitating better connections between science, engineering, and technology will require making these aspects of engineering more evident both to the public and to policymakers. One reason they are not well appreciated is that engineering has been so successful. The hallmark of good engineering, after all, is often its invisibility: the public simply takes for granted that airplanes fly, furnaces and computer networks work, vaccines are safe, and buildings stay up. Another reason is that the linear model remains the prevailing mindset of most academic research. Venkatesh Narayanamurti has recently pointed out the ways this picture is “faulty,” calling for the linear model to be replaced by a “combination of the scientific and engineering methods,” with “neither leading but each strengthening the other.”

Incorporating this expanded sense of nonlinear innovation with the knowledge that every engineering solution is unique can be the basis for a vision of science policy that nimbly adapts to solve society’s greatest problems. The engineering method aims for a specific goal—an airplane, a computer, a cathedral—but it has no prescribed process and so there is rarely a tidy, orderly, and complete explanation of an engineered solution. A policy model that assigns funding to specific institutions or facilities may miss the uniquely creative tools that engineering brings to bear. The engineering method is best described as an attitude or approach, or even a philosophy of creating a solution to a problem; the same person can act as a scientist and an engineer on the same day.

The murky meaning of “technology”

A final obstacle to leveraging the unique perspective of engineering, as Anna Harrison has noted, is that the word “technology” often subsumes and obscures the work of engineers. In fact, technology is the result of methods from both engineering and science as well as from business.

The hallmark of good engineering, after all, is often its invisibility: the public simply takes for granted that airplanes fly, furnaces and computer networks work, vaccines are safe, and buildings stay up.

The historian Leo Marx has illuminated how the word blurs distinctions and nuance. What exactly do we mean by “railway technology,” for example? We might mean the ancillary equipment—yards, bridges, tunnels, viaducts, signals, and miles of track—or the business office representing a large capital investment, or the specialized knowledge necessary to create the trains, rails, and telegraphs, or the institutional laws that mandate the gauge of the tracks or set standardized time zones. “When invoked on this plane of generality,” Marx concluded, “the concept of technology … is almost completely vacuous.”

The same might be said for the phrase “science and technology.” A poor understanding of the unique engineering perspective generates unrealistic expectations of “science and technology” and risks a loss of faith in the whole science-engineering-technology enterprise. It can also insulate engineering choices from public scrutiny and understanding and thus lead to products and systems that do not serve the full population. Artificial intelligence researchers Safiya Umoja Noble and Kate Crawford have shown how, in the absence of input from the social sciences, search engines can reflect embedded biases. As Noble explains, “We need people designing technologies for society to have training and an education on the histories of marginalized people, at a minimum, and we need them working alongside people with rigorous training and preparation from the social sciences and humanities.” The social sciences are desperately needed to inform both scientists and engineers in order to avoid unintended consequences of their discoveries and creations—and to point them in the direction of social benefit.

Engineering’s value and future

A policy model that assigns funding to specific institutions or facilities may miss the uniquely creative tools that engineering brings to bear.

For all these reasons, national policy must take much greater heed of what engineering has to offer, as both a distinctive method and a central component of innovation. Conceiving of engineering simply as applied science distorts the synergistic relationship of scientific knowledge and engineering practice, implying that engineers must wait for science to lead the way. In reality, engineering responds to wants and needs, not simply to the discoveries of scientists, and it often works at the cutting edge in a way basic scientists can’t—leading the way well before scientific understanding catches up. A distorted view of engineering also works to obscure what makes the field so exciting and creative, which might dissuade the best and brightest from pursuing an engineering career and thus rob society of the next generation of creative innovators—engineers who are needed to confront local and global challenges such as mitigation of climate change, control of pandemics, avoidance of famine, and other yet-unknown needs. Any science policy for the next century must ensure that we continue to foster engineers who, as von Kármán put it, will “create the world that never has been.”